International Units of Vitamin A


The vitamin-A content of a food is sometimes measured in International Units (IU) and at other times in "micrograms of retinol equivalents," or "micrograms RE." There is no direct comparison between an IU and a microgram RE, but you can get a crude estimate if you know whether the food is of animal or plant origin.

In the case of vitamin A supplements, the conversion may be more precise. First, check the label to see which source of vitamin A the supplement contains. Then:

(Some supplements may contain both sources. If the label specifies an amount for each, do the math for each and add the two together.)